Prior-art devices configured as wall saws for cutting a workpiece along a cutting line consist of a guide rail, a saw head that is arranged so as to be movable on the guide rail, and a motor-driven advancing mechanism to move the saw head along the guide rail. The saw head comprises a saw blade that is attached to a saw arm and that is driven around a rotational axis by a drive motor. The saw arm is configured so that it can be swiveled around a swivel axis by a swivel motor. The drive motor and the swivel motor are arranged in a device housing of the saw head. The motor-driven advancing mechanism comprises a guide carriage and an advancing motor that is arranged in the device housing of the saw head. The saw head is installed on the guide carriage and configured so that it can be moved by the advancing motor along the guide rail in the advancing direction. Aside from the motors, there is also a control unit that is installed in the device housing and that serves to control the wall saw.
Wall saws are operated either manually or in a process that is at least partially automated. In manual processes for cutting a workpiece along a cutting line, the operator has to approach the end points of the cutting line by manually controlling the motor-driven advancing mechanism during the processing. If the saw blade is surrounded by a blade guard, the exit points of the saw blade in the workpiece are hardly or not at all visible to the operator, so that the operator cannot determine the end points of a cutting line during the work process. The operator receives only a limited amount of information about the momentary work result. The momentary cutting depth of the saw blade in the workpiece can be read, for example, on a scale that is present on the blade guard. A drawback here is that the momentary cutting depth is not displayed in the case of cuts that are made without a blade guard. The blade guard, like the entire saw head, often becomes very dirty during the work process, so that the legibility of the scale can be further impaired. Moreover, during the work process, the operator has to maintain a certain safety distance from the wall saw, as a result of which the legibility of the scale can be even more limited, particularly in the case of horizontal cuts.
European patent application EP 1 693 173 A1 discloses a method that is at least partially automated in order to cut a workpiece along a cutting line, and it also discloses a wall saw that is suitable for carrying out said method. Aside from the usual components, the wall saw also comprises a sensor system having a swivel-angle sensor and a position sensor, whereby the swivel-angle sensor monitors the swivel angle of the saw arm, while the position sensor monitors the position of the saw head on the guide rail. This prior-art method for cutting a workpiece entails a sequence of three method steps that are carried out one after the other. In the first method step, the saw arm is slanted at a swivel angle that corresponds to the depth of the partial cut. In the second method step, the saw head is moved forward along the guide rail along the advancing direction until it reaches the first end point of the cutting line. In the third method step, the saw head is moved backwards along the guide rail along the advancing direction until it reaches the second end point of the cutting line. The cut is made in several partial cuts. These three method steps are continuously repeated until the desired cutting depth has been reached. The automated cutting method is intended to free the operator of some routine procedures so that he/she can concentrate on monitoring the work process. How the operator is supposed to monitor the work process is not disclosed.
It is an object of the present invention to provide a device for cutting a workpiece in such a way as make it easier for the operator to monitor the work process.
The present invention provides that on the basis of the measured quantities detected by the sensor system, the control unit calculates the momentary work result, and the momentary work result is shown on the display means. The momentary work result can be shown on the display means as a numerical value and/or in graph form. The operator can monitor the work process on the basis of the calculated momentary work result. In the case of a manual process, especially the momentary cutting depth of the saw blade and the position of the end points are the suitable quantities for monitoring the work process. All of the information about the work result that can be calculated on the basis of the measured quantities of the sensor system as well as of other known device parameters can be shown on the display means.
Preferably, the control unit has a memory element and it stores the measured quantities detected by the sensor system as well as the momentary work result in said memory element. If the measured quantities of the sensor system and the calculated momentary work result are stored in the memory element, the control unit can calculate additional characteristic values in order to monitor the work process, or else it can display the progress of the work process in graph form.
Especially preferably, on the basis of the measured quantities stored in the memory element and on the basis of the momentary work results, the control unit calculates additional characteristic values for the work process and shows these additional characteristic values on the display means. The additional characteristic values for the work process can be shown on the display means as a numerical value and/or in graph form. Aside from the momentary cutting depth of the saw blade in the workpiece, for example, the course of the cut in the workpiece is also of interest to the operator. The additional characteristic values for the work process include the main cutting depths, the positions of the end points of the cut and the length of the cut.
In a preferred embodiment, a remote control unit is provided that comprises the operating means and the display means and that is connected to the control unit via a communication connection. Showing the momentary work result on the remote control unit has the advantage that the operator can monitor the work process on the basis of the calculated momentary work results and of the additional characteristic values. During the work process, the operator holds the remote control unit in his/her hand and receives on the display means all of the information that is needed for monitoring the work process.
Especially preferably, the control unit comprises a first control unit and a second control unit, whereby the first control unit is arranged in the saw head, while the second control unit is arranged in the remote control unit. The operator can set the desired device and operating parameters using the operating means of the remote control unit. The second control unit converts the device and operating parameters into corresponding control commands for the saw head and for the motor-driven advancing mechanism. The control commands are transmitted by the second control unit to the first control unit via the communication connection. The first control unit gives the control commands to the saw head and to the motor-driven advancing mechanism.
In a preferred variant, the momentary work result is calculated in the first control unit, which is arranged in the saw head. The calculation and display of the momentary work result are supposed to take place in real time, so that the operator can monitor the work process on the basis of the momentary work result and can intervene in the work process if necessary. The shorter the transmission paths of the measured data, the shorter the time delay. The calculation of the momentary work result in the first control unit entails the advantage that only the work results that have to be shown on the display means are transmitted to the remote control unit via the communication connection.
In an alternative preferred variant, the first control unit transmits the measured quantities detected by the sensor system to the second control unit, and the momentary work result is calculated in the second control unit. The transmission of the measured quantities via the communication connection to the second control unit, which is arranged in the remote control unit, lends itself whenever the application calls for a special remote control unit and cannot be carried out with just any remote control unit.
Embodiments of the invention will be described below with reference to the drawing. The drawing does not necessarily depict the embodiments true-to-scale, but rather, the drawing—where necessary for the sake of explanation—is shown in schematic and/or slightly distorted form. Regarding any additions to the teaching that can be gleaned directly from the drawing, reference is hereby made to the pertinent state of the art. Here, it should be kept in mind that many modifications and changes relating to the shape and to details of an embodiment can be made without departing from the general idea of the invention. The features of the invention disclosed in the description, in the drawing as well as in the claims can be essential for the refinement of the invention, either individually or in any desired combination. Moreover, all combinations of at least two of the features disclosed in the description, in the drawing and/or in the claims fall within the scope of the invention. The general idea of the invention is not limited to the exact form or detail of the preferred embodiment shown and described below nor is it limited to a subject matter that would be limited in comparison to the subject matter put forward in the claims. At given rated ranges, values that fall within the specified limits are also disclosed as limit values and can be used and claimed as desired. For the sake of clarity, identical or similar parts or else parts with an identical or similar function are designated by the same reference numerals below.